This invention relates to the disposal of excess concrete product and more particularly to a method and apparatus involving the transfer of waste concrete from a utilization site to a disposal site.
In the construction industry it is a common practice in pouring large quantities of concrete to use concrete trucks ranging in capacity from 10 cubic yards to about 12 cubic yards to transport the plastic hydraulic concrete mix from a batching plant to the construction site. The timing and dispatching of concrete trucks is very important since the age of the concrete in the truck is significant. For example, a typical specification for concrete for a construction project may require that the concrete be xe2x80x9cfreshxe2x80x9d or xe2x80x9cplasticxe2x80x9d for as long as about one-half hour to two hours after batching to arrive at the construction site in a plastic concrete condition. If the concrete in a given truck is not sufficiently fresh to meet specifications, the concrete must be disposed of in some fashion. In many cases, the truck will be simply driven back to the batching plant and the concrete poured onto the ground where it is allowed to set and then broken up and ultimately hauled away to a landfill or other disposal site. Alternatively, the concrete truck may dispatch its load of concrete at some other location since it is obviously critical that the concrete not be allowed to set up in the interior of the concrete truck.
Even where the concrete is in spec in terms of its age, the truck, after dispensing its load, will contain some residual concrete which, even though it may amount to only a few cubic feet, must be removed from the drum of the truck prior to reusing the truck. Typically, the concrete is removed from the truck by washing out the interior of the drum with water. The water, as it exits the drum, carries with it the residual concrete. This concrete may be discarded, or in some cases, the water concrete mix can be passed to a reclaiming system where aggregates and perhaps water are reclaimed for further use. Alternatively, the residual concrete can be simply poured out on the ground at a suitable location at the batching plant for ultimate disposal.
The concrete, once it is allowed to harden, can, as noted above, be broken up and then hauled away in trucks such as dump trucks, trailer trucks, and the like. The containers for these trucks are variously configured to deal with loose materials, such as gravel, stone, and the like. For example, U.S. Pat. No. 5,460,431 to McWilliams discloses a dump truck which can be used to unload particulate loose materials including materials such as wet sand and clays or the like which tend to become clogged in the trailer or that may have a tendency to become stuck and thus difficult to dump from the trailer at the disposal location. In the McWilliams patent the container for the dumping material is characterized as being xe2x80x9cdouble-taperedxe2x80x9d to facilitate dislodgement of the contents from the trailer. The double taper is provided by a tapered bottom floor that is wider at the back than at the front of the dump truck and also tapered upwardly in the side wall configuration so that the side walls slope upwardly and outwardly and are taller near the front end of the container than at the rear end. The cross-sectional area of the trailer defines a equilateral trapezoid which has a vertical height somewhat greater than the transverse dimension of the bottom floor section and with the side walls flared upwardly at an obtuse angle of about 111xc2x0 to 112xc2x0 to provide a substantially larger horizontal upper dimension. Another dump truck body, which is configured with a rearwardly-flared container and with the side walls curved upwardly and outwardly, is disclosed in U.S. Pat. No. 1,989,125 to Atwell. The side walls of the truck are curved to provide a very rigid configuration. Yet, other truck bodies which are rearwardly tapered or otherwise configured to facilitate the removal of materials, such as gravel, clay, or wet earth, by dumping are disclosed in U.S. Pat. No. 1,627,336 to Nelson and U.S. Pat. No. 5,090,773 to Guillaume.
In accordance with the present invention, there is provided a waste container of the type to be employed with a transfer system for the disposition of waste concrete. The container comprises a bottom floor section having a major dimension extending longitudinally of the container and front and rear lateral dimensions which are substantially less than the major longitudinal dimension. The container is closed at its forward end by a forward transverse wall section. The container further comprises opposed side walls extending longitudinally of the container and upwardly from the bottom floor section to define with the bottom floor section a receptacle for waste concrete. The longitudinal side walls are flared from the front to the back of the container to provide a back opening which has a lateral dimension greater than the lateral dimension of the forward transverse wall section.
The side walls are sufficiently flexible to permit relative displacement between a first lateral dimension corresponding to the configuration of the side walls when they are not stressed and a second lateral dimension which is less than the first lateral dimension. The container configuration further comprises a reconfiguration system connected to at least one of the side walls. The reconfiguration system is effective to compress the lateral dimension of the side walls relative to one another from the first somewhat greater lateral dimension to the second reduced lateral dimension when a plastic mass, such as unset concrete or the like, is added to the container. Preferably, the reconfiguration system comprises an adjustable tension member connected at its end to the side walls at a location intermediate of the forward and back portions of the container. The bottom floor section of the container is substantially monoplanar to provide a flat surface upon which the waste plastic concrete can spread or be spread as it is poured into the container. Preferably, a major vertical dimension of the side wall section is substantially monoplanar and is oriented relative to the bottom floor section in an approximately perpendicular relationship.
In a further aspect of the invention, there is provided a method for the disposition of waste concrete employing a longitudinally-extending container having a bottom floor section and longitudinal side walls extending upwardly from the bottom floor section which are flared from the front to the back of the container. The side walls of the container are drawn toward one another before or concomitantly with the addition of a mass of plastic concrete to the interior of the container. By compressing the side walls inwardly toward one another, the plastic concrete is allowed to set with the side walls in the compressed inward relationship. After the concrete has at least partially hardened to become self-supporting, the side walls are removed from the compressed relationship to an extended relationship in which the side walls move outwardly from one another to provide a clearance space between the hardened mass of concrete and the side walls. The hardened mass of concrete is then withdrawn from the container through the back portion thereof.
In yet a further embodiment of the invention, there is provided a method for the distribution of waste concrete at a terminal station, such as a concrete batching plant, from which concrete trucks are dispatched and returned. A transfer system, including an elongated container with a bottom floor section and flared side walls, is located at the terminal station. The side walls of the container are compressed inwardly toward one another at an intermediate location between the front and rear of the container, and a mass of plastic concrete from a concrete truck arriving at the terminal station is dispensed from the truck into the container. The concrete so dispensed may constitute a residual concrete content which may range from several cubic feet to as much as a cubic yard or more of concrete. This procedure is repeated a plurality of times with residual concrete removed from concrete trucks as they arrive at the terminal station. Once the container is filled to the desired capacity, it is then transported to a desired location for the disposition of waste concrete in the container. After the concrete has at least partially hardened to become self-supporting, the side walls are removed from the compressed relationship to the extended relationship to provide a desired clearance between the mass of concrete and the side walls. The hardened mass of concrete can then be withdrawn from the back portion of the container.